A conventional method of forming a Ga2O3 single crystal is known in which a Ga2O3 single crystal is grown while adding a Group IV element such as Si and Sn so as to impart conductivity to the Ga2O3 single crystal (see e.g. PTL 1).
An another conventional method of forming a Ga2O3 single crystal is also known in which a β-Ga2O3 crystal is heteroepitaxially grown on a sapphire substrate while adding an impurity such as Sn so as to form a β-Ga2O3 crystal film with conductivity (see e.g. PTL 2).
A method of introducing an impurity ion into a SiC crystal by ion implantation is also known (see e.g. PTL 3).